import pandas as pd

df = pd.DataFrame({'商品': ['苹果', '香蕉', '鸭梨'],
                   '单价(元)': [5, 5, 4],
                   '销量(kg)': [100, None, None],
                   '库存(kg)': [50, None, 70]})
print('原始数据: \n', df)
print('删除包含缺失值的行: \n', df.dropna(axis=1))
print('删除少于3个非缺失值的行: \n', df.dropna(thresh=3))
print('删除库存列包含缺失值的行: \n', df.dropna(subset=['库存(kg)']))
